Air pollution is caused by gases and particles emitted to the atmosphere by a variety of human activities, such as the inefficient combustion of fuels, agriculture, and farming. There are also natural sources contributing to air pollution, including particles of soil dust and salt in sea spray. Air pollutants can be emitted directly from a source (i.e. primary pollutants) or can form from chemical reactions in the atmosphere (i.e. secondary pollutants). When concentrations of these substances reach critical levels in the air, they harm humans, animals, plants and ecosystems, reduce visibility and corrode materials, buildings and cultural heritage sites. The main pollutants affecting human health are particulate matter, ground-level ozone (O3) and nitrogen dioxide (NO2). The fine particles that damage human health are known as PM2.5 (particles with a diameter of less than 2.5 micrometres), which can penetrate deep into the lungs and pass into the bloodstream affecting different organs and bodily functions. These particles are can either be emitted directly or formed in the atmosphere from several different emitted pollutants (e.g. ammonia (NH3), and volatile organic compounds (VOCs)). Ozone (O₃), is an important secondary pollutant. It is a potent lung irritant and stunts growth in plants. It is also a powerful greenhouse gas (GHG). O₃ is formed in the troposphere, near the Earth’s surface, when certain precursor pollutants react in the presence of sunlight. The powerful GHG, methane (CH₄), is responsible for a significant portion of O₃ formation. This tropospheric ozone is different from the ozone in the upper atmosphere (stratosphere), which protects us from ultraviolet light from the sun. Nitrogen oxides (NOx) are a group of air polluting chemical compounds, comprising nitrogen dioxide (NO2) and nitrogen monoxide (NO). NO2 is the most harmful of these compounds and is generated from human-driven activities. It impacts human health, reduces atmospheric visibility, and can play a significant role in climate change, at high concentrations. Finally, it is a critical precursor to the formation of O₃.

Air pollution has been associated with humans for millennia, starting with the use of fire for cooking and warmth. Dangerously high levels of outdoor air pollution became a problem during the industrial revolution, where the massive use of coal gave rise to many episodes of serious urban air pollution. The case of the London fog in 1952, is an extreme example, causing a surge in deaths over a one-week episode. The pollution from residential coal fires, coal for electricity generation, the use of dirty fuels for transport, and industrial pollution, interacted with weather phenomena which trapped the pollution over London and led to over 12,000 excess deaths over these few days. The public outcry that followed, led to the adoption of the UK Clean Air Act (1956). Other fatal air pollution episodes, e.g. in Donora, USA (1948), and Meuse Valley, Belgium (1930), prompted similar actions to be taken to tackle air pollution in other countries. Continued reliance on fossil fuels through the 20th century saw air pollution increase as countries industrialized. In newly industrialized countries like China and India, this has led to extreme air pollution events, like those experienced in the past in the USA and Europe. However, new forms of cleaner and renewable energy, and the adoption of air quality regulations and management processes, are reducing reliance on some polluting fuels and practices. Beijing, once notorious for its air pollution problem, has in the last 20 years taken increasingly aggressive steps to reduce air pollution and its air quality has improved substantially.

Air pollution is all around us. Most people in the world live in areas with high levels of air pollution. It harms human health and wellbeing, reduces quality of life, and can negatively impact the economy. These impacts also disproportionately affect the most vulnerable people and communities. Air pollution is the largest environmental risk to public health globally. People everywhere are exposed to air pollution, in the workplace, during travel and in their homes. Exposure to household and ambient (outdoor) fine particulate matter air pollution causes an estimated 7 million premature deaths each year, according to the World Health Organisation (WHO), and is responsible for a substantial amount of disability for those living with diseases caused by air pollution. Air pollution is a solvable problem and more affluent nations have greatly improved their air quality in recent decades. But air pollution is now inequitably affecting people in low- and middle-income countries. In many developing countries, reliance on wood and other solid fuels, like raw coal for cooking and heating, and the use of kerosene for lighting, increases air pollution in homes, harming the health of those exposed. It is estimated that more than 2.7 billion people rely on these types of fuels. Most of the effects are felt in parts of Asia and sub-Saharan Africa, where burning biomass for cooking is especially prevalent. While the impacts on human health are the most pressing, air pollution also significantly impacts several different types of ecosystems and it reduces crop yields and the health of forests. It also reduces atmospheric visibility and increases corrosion of materials, buildings, monuments and cultural heritage sites, and causes acidification of sensitive lake ecosystems. These health and environmental impacts need to be reduced for their own sake, but air pollution also has huge economic costs related to human health, lost productivity, reduced crop yields and reduced competitiveness of globally connected cities. For example, the global cost of health damages in 2016 alone from outdoor air pollution was estimated to be US$5.7 trillion, equivalent to 4.8 percent of global Gross Domestic Product (GDP) that year. Air pollution is also strongly linked to climate change, with many greenhouse gases (GHGs) and air pollutants coming from the same sources. Many air pollutants are both bad for human health and powerful climate forcers, thus impacting people’s lives today and making the future less safe for coming generations. Coordinated measures to reduce air pollution and GHGs, such as those addressing Short-Lived Climate Pollutants (SLCPs), can produce very large benefits to public health and the environment. Air pollution’s links to development, the economy and the environment means reducing air pollution is tied to the achievement of the Sustainable Development Goals (SDGs), and directly affects the achievement of SDG 3: Good Health and Wellbeing , SDG 7: Affordable and Clean Energy, SDG 11: Sustainable Cities and Communities, and SDG 13: Climate Change. It indirectly impacts many other SDGs. Air pollution has also been implicated in the current COVID-19 pandemic. Studies carried out during the early months of the pandemic showed direct links between levels of air pollution and increased vulnerability to succumbing to the disease. Studies also argued that the spread of COVID-19 might be aided by particulate air pollution. These studies need further investigation but are yet another reason for action on air pollution. From past and current experience, we know that air pollution is preventable, and as the examples show, reducing air pollution will provide additional benefits like healthier and more productive lives, a healthier natural environment, poverty alleviation and increased shared prosperity.

Air pollution comes from a wide array of sources, both natural and human-driven (anthropogenic). Natural sources include volcanic eruptions, sea spray, soil dust, natural vegetation fires and lightning. Some of the most common human-driven sources include power generation, transportation, industry, residential heating and cooking, agriculture, solvent use, oil and gas production, waste burning and construction. Some sources, such as forest and savanna fires, and windblown mineral dust, occur naturally, but are exacerbated by human activities. For much of the world’s population, human activities account for most of the air pollution they are exposed to. Different pollutants have different sources. In cities, air pollution comes from both inside and outside city boundaries, some of it travelling over long distances. Major urban sources include vehicles, burning of gas, coal and charcoal, wood for cooking and heating, and industrial sources still located in cities. Many large industrial sources, such as cement plants, steel plants and electricity generation, are located away from cities, but still contribute a lot to the urban concentrations, due to being carried long distances by the air. Emissions from the oil and gas industry and the maritime sector can also travel over very long distances. Agricultural sources, including burning to clear land, and forest fires, contribute a lot to urban and rural air pollution levels. In very dry areas, close to deserts and eroded land, wind-blown dust can make up a large fraction of the PM2.5. Most ammonia is emitted from agriculture and human waste treatment. One of the most common sources of air pollution in rural and peri-urban areas of low-income countries, comes from households burning biomass, other solid fuels (e.g. coal) or kerosene for cooking, heating and lighting. Household air pollution also contributes to outdoor air pollution.

Air pollution significantly impacts places near its source, but because it can be carried long distances in the atmosphere, air pollution created in one place, can also affect faraway places. For example, pollutants that form into fine particulate matter (PM2.5) and ozone (O3) can travel over hundreds or thousands of kilometres, causing regional and continental impacts. This transboundary air pollution leads to challenges for regulations and enforcement because different countries or regions, have little regulatory control over air pollution coming from outside their borders (Also see question 14). Despite the contribution of long-distance air pollutants to local air pollution, nearby sources remain a very significant determining factor of local air quality. Pollutants like nitrogen dioxide (NO2) and sulphur dioxide (SO2), have concentration levels which are highest close to their sources (transport, energy production and industries). Within a city, areas closest to large sources can have huge pollutant concentrations, while other areas of the same city can be much cleaner. Atmospheric conditions, such as wind, affect pollutant dispersion and can vary widely. Strong winds enable long-distance transport, and stagnant conditions can lead to a build-up of pollutants. Large cities in subtropical and tropical regions that have very light winds and many hours of sunshine, experience serious pollution episodes. Mountains surrounding cities, land-sea breezes and other local weather conditions can affect the spread of pollutants and influence the formation of secondary pollutants.

The air pollutant of greatest concern for human health is fine particulate matter. This has a diameter of 2.5 micrometers or less, also known as PM2.5. These fine particles are invisible to the human eye and 40 times smaller than the width of a human hair. They can do a lot of damage to our bodies. These particles are small enough to penetrate deep into our lungs, where they cause inflammation of sensitive lung tissue and can pass into the blood stream, affecting organs like the heart and brain. The WHO estimates that exposure to PM2.5 causes 7 million premature deaths annually. Air pollution causes both acute disease and chronic disease. There is strong evidence linking long-term exposure to air pollution with an increased risk for ischemic heart disease, stroke, chronic obstructive pulmonary disease (COPD), lung and upper aerodigestive cancers, adverse pregnancy outcomes (i.e. low-birth rate, pre-term births and reduced birth weight (babies born weighing less than five pounds), diabetes and cataracts. The WHO’s International Agency for Research on Cancer (IRCA), has designated air pollution as a carcinogen. Some immediate health effects of air pollution exposure include irritation of the eyes, nose and throat, shortness of breath, cough, and exacerbation of pre-existing conditions, like asthma attacks, and chest pain. Age, pre-existing conditions, other risk factors for disease and sensitivity to the pollutant, can all affect how a person reacts to a pollutant. Air pollutant gases can also be very dangerous. Carbon monoxide (CO), restricts the transfer of oxygen to tissues and can be fatal in very high concentrations. Sulphur dioxide (SO2), is a potent lung irritant affecting the health of those with pre-existing respiratory disease (asthma and COPD), especially those living and working close to SO2 sources. Nitrogen oxides (NOx) are linked to a range of impacts, spanning from respiratory irritation, to the development of asthma and increased mortality. Exposure to ozone (O3) causes respiratory diseases and was associated with 472,000 premature deaths in 2017, according to the Global Burden of Disease (IHME).

While all individuals experience different levels of health impacts from air pollution, across large city or country populations, there is no evidence of a completely safe level of air pollution, especially in the case of particulate matter. However, to help guide countries achieve cleaner air for health, the WHO has set normative guideline values for all major air pollutants, above which, negative impacts on population health are likely. For example, the WHO estimates that reducing annual average fine particulate matter (PM2.5) concentrations from levels of 35 micrograms per cubic meter (μg/m3), (an interim air quality guideline commonly used in many developing country cities), to the WHO guideline level of 10 μg/m3, could reduce air pollution related deaths by around 15%. This does not mean that there are no health effects below those guidelines, but they represent health-based targets useful for tracking the burden of disease from air pollution, informing national level targets and standards, and monitoring the effectiveness of air quality management efforts designed to improve health. Many countries have established national air quality standards. National standards may differ from country to country and may be above or below the respective WHO guideline value. It is a policy issue to decide which specific at-risk groups should be protected by the standards, and what degree of risk is considered to be acceptable. However, many countries are working towards meeting the WHO air quality criteria and its interim goals. The UNECE Convention on Long-range Transboundary Air Pollution has also provided threshold (critical) levels for ozone (O3), above which, impacts on crops and other vegetation can occur.

Ozone (O3) is by far the main air pollutant affecting plant growth. It reduces crop yields, forest health and biodiversity generally. Different plant species have different sensitivity to O3; those more sensitive to O3 will have reduced competitive advantage in ecosystems, while more resistant species will become more dominant. Some crops are very sensitive to O3, especially beans. Soybean yields, for example, can be reduced by 15% or more. There is also a knock-on effect on the climate, as the reduced growth of forest trees caused by O3 pollution, reduces the ability of forests to absorb carbon dioxide and their potential to help regulate climate change. Other pollutants like Sulphur and nitrogen can also damage forest and lake ecosystems, through acidification of soils and surface water, affecting forest growth and killing fish and other organisms. Nitrogen deposition also causes eutrophication (over-fertilizations) of low nutrient ecosystems such as heathlands, causing large shifts in biodiversity.

Many cities have implemented monitoring networks that continuously measure air pollutants as part of their air quality management systems. Many of them regularly report an Air Quality Index (AQI) that is easy to interpret, and often color-coded, to warn of dangerous levels of air pollution. The information is accessible through websites, newspapers and apps. Countries define their own indices based on their own air quality standards. Therefore, they are not comparable between countries and are designed for public information purposes. The availability of air quality monitoring is unequal globally and regionally. This is because high quality monitors are expensive, as is the cost of training people to run and maintain monitoring networks. Even in places with good monitoring, there are discrepancies. For example, in some cities, there are very dense monitoring networks, while in other parts the networks are less dense. In many developing countries across the world there is no official air pollution monitoring. Investing in air quality monitoring is very important because the larger the networks are, the more information we can have for a city, a region or country. This information can be invaluable for helping people understand the air pollution levels where they live and take action to reduce their exposure. It’s also important for governments, to be able to make short and long-term planning decisions to reduce air pollution. In many places, private companies are developing lower-cost air quality monitors that people can install in their own homes. This is leading to networks of citizen scientists reporting on air quality and citizen led online air quality databases. A number of international and civil society organizations, and private companies, also collect and report air quality information, often based on a combination of monitoring and satellite data. Where local information is unavailable, these can be useful resources to understand the air pollution problem in your city or country.

Governments are responsible for providing their citizens with clean air. There are multiple options for national and local governments to improve air quality. Air pollution is a problem that we know how to solve. Governments need to invest in capacity to measure and monitor air pollution by establishing monitoring networks; and ensuring that such networks are properly operated, maintained, and subjected to procedures that guarantee the quality and reliability of air quality measurements. The first step towards responsible management of air pollution is to make sure that necessary regulations, policies, and enforcement mechanisms are in place and sufficiently supported. Governments should ensure that the appropriate institutions have sufficient capacity to monitor and assess air pollution emissions. This will ensure that decision makers know where their air pollution comes from, how large the different sources of emissions are, the levels of air pollution in different parts of their country, the impacts to health, and what high impact actions can be taken to reduce pollution levels and reduce the harm caused. Where capacity to undertake such activities is limited or local data is not available, there are still resources available to help countries understand their air pollution problem and identify priority actions that can be taken. These include sources for emissions, estimated by global programs, or concentrations and health impacts (WHO,IHME, State of Global Air), estimated from satellites and global modelling, with ground truthing from monitoring stations. These datasets have their limitations and uncertainties and should be used in the cases where local data are not available, or where there is limited monitoring capacity. It is important that governments understand the benefits and costs associated with alternative actions or interventions to improve air quality; and to prioritize actions. Most air pollution reduction measures have health and social benefits that far outweigh the costs of implementation. Strengthening institutions and governance, promoting behavioral change, instilling a pro-clean air culture, increasing the capacity in all sectors to effectively engage and contribute to solutions, political will, and increased funding, are also key elements of success.

Air pollution has not been solved in any region, but there have been remarkable decreases in emissions and pollutant concentrations in many European countries, as well as the USA, Canada and Japan, where strong policies, regulations and regular monitoring systems were put into place. One of the most famous examples is London, which had some of the worst levels of pollution, earlier than other cities, probably peaking in the year 1900. Since then, air quality in the UK has improved remarkably. Particulate air pollution levels fell by over 97% between 1900 and 2016. Other cities and regions have also shown significant reductions, brought about by similar policies. However, this does not mean that air pollution has been solved. In London – PM2.5 remains higher than the WHO air quality standard. Mexico City is another example of how cities have reduced their air pollution significantly. The city had a very serious ozone (O₃) pollution problem in the 1980s. From a peak in 1989, O₃ levels have decreased by two-thirds by 2015 – still high enough to cause significant health impacts, but a massive reduction nevertheless. These decreases show that air pollution is a problem that we know how to solve, and that there are policies and technologies needed to achieve cleaner air. In many countries, improved air quality has happened while countries have increased in wealth. This means that unlike in the past, where air pollution was considered an unavoidable cost of economic growth, air pollution reduction does not impact economic growth. It is effectively decoupled from wealth creation.

Since some air pollutants travel long distances and across borders, a multi-national/regional approach is important to manage cross-border air pollution. International cooperation facilitates knowledge sharing of experiences and good practices, and raises the profile and resources needed to address the air pollution crisis, at a scale consistent with the magnitude of the problem. A good example of the positive achievements of a multi-national intergovernmental air pollution reduction approach is the UNECE Convention on Long-range Transboundary Air Pollution , which was the first coordinated approach between countries to address their common and shared air pollution problems. Scientific cooperation has also been initiated in Asia. The development of regional agreements to address the shared problem of transboundary air pollution During the 1960s, scientists found that the deposition of air pollutants, often emitted thousands of kilometers away, were causing the ‘acid rain’ that was affecting forests, causing acidification and associated fish loss in lakes, and putting entire ecosystems at risk in parts of the Northern Hemisphere, particularly in Scandinavia, Canada and Scotland. Two landmark conferences in the 70s, the United Nations Conference on the Human Environment and the Helsinki Conference on Security and Cooperation in Europe, paved the way for negotiations on an intergovernmental agreement to reduce air pollution. In 1979, 32 countries signed the UNECE Convention on Long-range Transboundary Air Pollution: the first international treaty to deal with air pollution on a broad regional basis. Entering into force in 1983, the Convention laid down the general principles of international cooperation for air pollution reduction and set up an institutional framework that has brought together science and policy. With 40 years of experience, 51 Parties in the Northern Hemisphere and 8 Protocols in force today, the results of the work under the Convention so far, have been significant. The Convention is unique in that it provides an international legally binding agreement, which sets emission reduction targets for several pollutants. It provides a platform for countries to discuss policies and to exchange best practices. The Convention counts on a solid science-policy interface, a compliance mechanism and a capacity-building support program.

There are several challenges countries face when addressing air quality. The cost of certified monitoring equipment, as well as regular calibration and maintenance, can be a heavy burden to many local authorities and national governments. It is important to note that the cost of air quality monitoring is much lower than the cost of air pollution reduction, the former being a public investment and the latter a private investment. It therefore makes sense for national governments and cities in developing countries to prioritize and invest in the establishment, operation and maintenance of ground-level air quality monitoring networks, to generate reliable data on air quality. Many countries have no government run monitoring networks using regulatory-standard equipment at all. In countries with limited resources, monitoring sites are often only located in their largest, most populated city. Many cities in developing countries can only afford to have a single monitoring site, or a few at most. This is something that needs to be addressed.

Businesses and industry have a key role to play in reducing air pollution, since many of their activities are sources of different types of air pollutants. The private sector can contribute to air pollution through its various operations and supply chains across different sectors. Pollution sources from the private sector range from burning fuels, to distribution and delivery vehicles. Since air pollution also contributes to climate change, companies that pledge to reduce their air pollution emissions can simultaneously reduce their carbon footprint. This double win, of reducing air pollution and their carbon footprint, can and has been the driver of innovative solutions from the sector. In the past, these solutions have mostly been technological (e.g. switching from one technology to another), but some parts of the private sector may need to move beyond those technological solutions. There are several actions the private sector can take to reduce air pollution:

Most sources of air pollution are structural and embedded in the economic processes underpinning modern society. It is therefore difficult for individuals to stop air pollution on their own. It will take a collective effort. The most important thing people can do is to get informed about the levels of air pollution where they live and how it affects them, and to put pressure on politicians, leaders, and decision makers to reduce air pollution in their city / region / country. Some of the things individuals can do to reduce their personal contribution to air pollution are: choose clean modes of transport when available (e.g. public transport, cycling or walking rather than private cars or motorbikes); if you’re considering buying a car, look at its nitrogen dioxide emissions and check the real world emissions for that car. Avoid buying diesel cars. Buying a hybrid or electric vehicle will also help to cut down your emissions; if you have a car, ensure it is serviced regularly to minimize its contribution to air pollution; use clean fuels and technologies for cooking, lighting and heating; use renewable energy sources wherever possible; stop burning household and agricultural waste; eliminate fireplace and wood stove use; monitor your energy demand and waste at home and install energy-efficient appliances and light bulbs, insulation and draught-proof windows.

Air pollution is a threat to sustainable development, as it simultaneously affects various social, environmental and economic criteria linked to equitable human development, such as good health, food security, gender equality, climate stability and poverty reduction. Air pollution also goes to the heart of social justice and global inequality. According to the World Health Organization (WHO), 97 per cent of cities in low- and middle-income countries, with more than 100,000 inhabitants, do not meet air quality guidelines. That percentage falls to 49 in high-income countries.

In at least 155 countries, a healthy environment is recognized as a constitutional right. Obligations related to clean air are implicit in a number of international human rights instruments, including the Universal Declaration of Human Rights and the International Covenant on Economic, Social and Cultural Rights. In 2019, at the 40th session of the Human Rights Council, the right to breathe clean air was highlighted in a report by the Special Rapporteur for Human Rights and the Environment. The report highlights the seven steps that States must implement , to fulfil the right to breathe clean air.

Smoke from wildfires as well as other landscape fires used for land clearing and agriculture are a major contributor to air pollution, contributing to roughly 4% of global PM2.5 but responsible for 10 – 60% in many countries of the world. Extreme fire smoke events can lead to very high levels of air pollution over 1-2 weeks periods, easily the highest levels experienced throughout the year in affected locations. Prominent examples are Australian bushfires, land clearing and peat fires in Indonesia, as well as wildfires in Canada, Russia and in the western US. In the western US, it is estimated that approximately 46 million people were exposed to at least one wildfire smoke event during the 2004-2009. Wildfire smoke clearly leads to a worsening of pre-existing respiratory disease, such as asthma and chronic obstructive pulmonary disease (COPD), with emerging evidence of impacts on cardiovascular disease, increased complications for those with type 2 diabetes as well as links between in utero exposure and low birthweight babies. It is not yet known whether discrete smoke episodes that are experienced year after year have cumulative impacts, although evidence from air pollution in general suggests this is also likely. From the perspective of overall, population-level impacts, an analysis conducted in 2012, estimated that smoke from landscape fires accounted for approximately 10% of the estimated annual deaths attributable to particulate matter air pollution. As wildfire smoke events will increase with a warmer climate and given that these are inherently more difficult to control at the source compared with other common air pollution sources, there is a need for adaptation strategies. Communities in wildfire-prone areas must plan for clean-air shelters, while individuals, especially the most susceptible can use HEPA filter portable air cleaners to reduce exposures. and to ensure they have sufficient medication to last through a prolonged wildfire season.

Vehicles and other mobile sources, including trucks, locomotives, buses, motorcycles, agricultural equipment and construction equipment, contribute more than 70 percent of the oxides of nitrogen (NOx) and volatile organic compounds (VOCs) that form ground-level ozone air pollution. It is safe to exercise in the morning. Ozone levels climb throughout the day resulting in higher readings in the afternoon and early evening hours. Morning is a good time for biking, walking, jogging or other types of strenuous outdoor activities. We recommend checking current air quality conditions here on saccleanair.com or using the Sacramento Region Air Quality app before participating in any outdoor exercise during the summer.

The best way to reduce ozone pollution is to drive less. Mobile sources are the largest contributor to ozone in the Sacramento region. Reducing emissions when Spare The Air is in effect can prevent unhealthy levels of ozone pollution. Carpooling, riding transit, telecommuting, trip-linking, bicycling and walking are all excellent ways to reduce your driving.

Poor visibility is caused by two factors: The reddish-brown haze you often see hanging over the valley is caused by higher concentrations of oxides of nitrogen, better known as NOx. NOx is converted into ozone air pollution when it reacts with volatile organic compounds (VOCs) and "cooks" in the direct ultraviolet rays from the sun. Fine particles, consisting mainly of by-products from internal combustion engines like automobiles, construction and agricultural equipment, contribute to reduced visibility. The air districts of the Sacramento region are committed to developing programs to reduce NOx and fine particle pollution, which will decrease ozone concentrations and improve visibility.

The U.S. AQI is EPA’s index for reporting air quality.

Think of the AQI as a yardstick that runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality. For each pollutant an AQI value of 100 generally corresponds to an ambient air concentration that equals the level of the short-term national ambient air quality standard for protection of public health. AQI values at or below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is unhealthy: at first for certain sensitive groups of people, then for everyone as AQI values get higher. The AQI is divided into six categories. Each category corresponds to a different level of health concern. Each category also has a specific color. The color makes it easy for people to quickly determine whether air quality is reaching unhealthy levels in their communities.

The AQI is divided into six categories. Each category corresponds to a different level of health concern. Each category also has a specific color. The color makes it easy for people to quickly determine whether air quality is reaching unhealthy levels in their communities.

The potential links between exposure to poor air quality and susceptibility to the impacts of COVID-19 are being investigated by the health and scientific community. Air pollution is known to have detrimental effects on the respiratory and cardiovascular systems, as well as impacts on other diseases that have been shown to raise the risk of COVID-19 severity. It is crucial to consider improved air quality as an additional measure, to help reduce the burden placed on people’s health, as well as healthcare systems. Long-term exposure to outdoor air pollution (PM, NO2, and O3) is likely to increase COVID-19 infection risk and severity. As our understanding of these links improve, it is even more important to commit to long-term sustainable energy, environmental policies and standards implementation. Despite the acute challenge of this global pandemic, we cannot allow it to compromise our efforts to tackle the world’s inescapable, linked, and ongoing challenges of climate change, poor air quality, unsustainable development and the loss of biodiversity.

Even healthy people can experience impacts from polluted air including respiratory irritation or breathing difficulties during exercise or outdoor activities. Your actual risk of adverse effects depends on your current health status, the pollutant type and concentration, and the length of your exposure to the polluted air. High air pollution levels can cause immediate health problems including: · Aggravated cardiovascular and respiratory illness · Added stress to heart and lungs, which must work harder to supply the body with oxygen · Damaged cells in the respiratory system Long-term exposure to polluted air can have permanent health effects such as: · Loss of lung capacity and decreased lung function · Development of diseases such as asthma, bronchitis, emphysema, and possibly cancer · Shortened life span Those most susceptible to severe health problems from air pollution are: · Individuals with heart disease, coronary artery disease or congestive heart failure · Individuals with lung diseases such as asthma, emphysema or chronic obstructive pulmonary disease (COPD) · Pregnant women · Outdoor workers · Older adults and the elderly · Children under age 14 · Athletes who exercise vigorously outdoors People in these groups may experience health impacts at lower air pollution exposure levels, or their health effects may be of greater intensity.

Exposure to high levels of air pollution can cause a variety of adverse health outcomes. It increases the risk of respiratory infections, heart disease and lung cancer. Both short and long term exposure to air pollutants have been associated with health impacts. More severe impacts affect people who are already ill.

Smoke is made up of a complex mixture of gases and fine particles produced when wood and other organic materials burn. The biggest health threat from smoke is from fine particles. These microscopic particles can penetrate deep into your lungs. They can cause a range of health problems, from burning eyes and a runny nose to aggravated chronic heart and lung diseases. Exposure to particle pollution is even linked to premature death.